Vehicle navigation systems are found in an ever increasing proportion of new cars and light trucks. The primary source of position, velocity and time data in a typical vehicle navigation system is a global navigational satellite system (GNSS) receiver. (The United States' NAVSTAR Global Positioning System (GPS) is the most widely used GNSS; however, modern GNSS receivers may use signals from GPS and other GNSSs such as the Russian GLONASS, Chinese BeiDou and European Galileo systems.)
The accuracy of GNSS receivers suffers if a clear view of several satellites is not available. GNSS receivers can have difficulty in urban canyons, parking garages, tunnels, bridge lower decks or dense forests, as examples. Dead reckoning, meaning estimating position based on heading and distance traveled since the last GNSS position fix, is a way to fill in gaps in GNSS coverage. Dead reckoning is based on data obtained from sensors such as accelerometers, gyroscopes and odometers.
Gyroscopes used in vehicle navigation systems are inexpensive micro-electromechanical systems (MEMS). In 2015 a MEMS gyroscope cost only about $1. As in many things, you get what you pay for, and low-cost MEMS gyroscopes, while being an essential component of dead reckoning systems, have severe limitations. In particular, low-cost MEMS gyroscopes are not supplied with unit-specific characterization data or precise self-calibration mechanisms. A hundred gyros, all of the same type, may all produce different readings under identical operating conditions. Left uncorrected, these variations can lead to navigation errors.
Therefore, what are needed are systems and methods to track and estimate errors in low-cost MEMS gyroscopes found in vehicle navigation systems.